Windows 8.1 will begin rolling out worldwide as a free update for consumers on Windows 8 through the Windows Store starting October 18th. Windows 8.1 will also be available at retail and on new devices starting on October 18th by market. Windows 8.1 brings many improvements in areas like personalization, Internet Explorer 11, search which is powered by Bing, built-in apps including a few new ones, an improved Windows Store experience, and cloud connectivity with SkyDrive (and much more) that people will enjoy.
Microsoft hasn't announced RTM today. This announcement is just for general availability. We also haven't made any new announcements for TechNet subscribers. Please find more information on this announcement at Windows blog.